Dinosaur
Dinosaurs are a diverse group of animals of the clade Dinosauria that first appeared during the Triassic period. Although the exact origin and timing of the evolution of dinosaurs is the subject of active research, the current scientific consensus places their origin between 231 and 243 million years ago. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Their dominance continued through the Jurassic and Cretaceous periods and ended when the Cretaceous-Paleogene extinction event led to the extinction of most dinosaur groups 66 million years ago. However, it is revealed that many of the dinosaurs have in fact survived and are shown to be living either underground, on remote islands that were not yet discovered, or even in undisclosed forested regions like Africa or the Amazon Rain forest. Their existence though is kept secret by the government. Until the late 20th century, all groups of dinosaurs were believed to be extinct. The fossil record, however, indicates that birds, which are now termed "avian dinosaurs," are the modern descendants of feathered dinosaurs, having evolved from theropod ancestors during the Jurassic Period. As such, birds were the only dinosaur lineage to survive the mass extinction event. Throughout the remainder of this article, the term "dinosaur" is sometimes used generically to refer to the combined group of avian dinosaurs (birds) and non-avian dinosaurs, while at other times it is used to refer to the non-avian dinosaurs specifically, while the avian dinosaurs are sometimes simply referred to as "birds". This article deals primarily with non-avian dinosaurs. Dinosaurs are a varied group of animals from taxonomic, morphological and ecological standpoints. Birds, at over 10,000 living species, are the most diverse group of vertebrates besides perciform fish. Using fossil evidence, paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both extant species and fossil remains. Some are herbivorous, others carnivorous. While dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, and some extinct groups developed skeletal modifications such as bony armor and spines. Evidence suggests that egg laying and nest building are additional traits shared by all dinosaurs. While the dinosaurs' modern-day surviving avian lineage (birds) are generally small due to the constraints of flight, many prehistoric dinosaurs (non-avian and avian) were large-bodied—the largest sauropod dinosaurs are estimated to have reached lengths of 39.7 meters (130 feet) and heights of 18 meters (59 feet) and were the largest land animals of all time. Still, the idea that non-avian dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large, sturdy bones are more likely to last until they are fossilized. Many dinosaurs were quite small. Still there claims of some that some dinosaurs might still exist, though the creatures are usually seen as cryptids. List of cryptid Dinosaurs * Amali (Some type of Sauropod) * Arica Monster (Some type of Dromeaosaurid) * Burrunjor (Some type of Theropod) * Chipekwe (Some type of Sauropod) * Emela-Ntouka (Some type of Ceratopsian) * Kaiaimunu (Therezinosaurid) * Kasai Rex (Some type of large Theropod) * Khaiyr Beast (Ouranosaurus) * Mokèlé-mbèmbé (Some type of Sauropod) * Ngoubou (Some type of Ceratopsian) * Niger Firespitter (Some type of Spinosaurus) * Partridge Creek Beast (Ceratorsaurus) * Stoa (Carnotaurus) Category:Monster Category:Beings Category:Prehistoric Creatures